Despite the relatively small number of current users, the Nielson survey of over 30,000 wireless subscribers found that there is enthusiasm for mobile commerce.

The research found a dramatic rise in the number of people using mobile Web to access shopping and auction sites. Of the 40 million active mobile Web users in April, five million visited shopping and commerce sites - a 73% rise from April 2007. Auction site eBay alone attracted 3.4 million visitors in April.

Text messaging is also an increasingly popular method for making purchases, with 6.5 million US mobile consumers saying they've used SMS to buy an item.

Commenting on the findings, Nic Covey, director of insights, Nielsen Mobile, says: "For many of the millions of consumers who are already shopping online or over landline phones, mobile commerce is an obvious and useful extension of that opportunity."

But security continues to be the biggest barrier to mobile commerce take-up, with 41% of data users who do not shop with their phone citing this as their main concern. Nearly a quarter worry about being charged for the airtime and 21% don't trust that the transaction will be completed.

Says Covey: "As more mobile commerce services become available and consumers develop a greater trust for phone-based transactions, we expect commerce to be an increasingly important part of the mobile experience next year and beyond."

Recent research from Cisco Systems predicts that mobile phones will become a major purchasing channel for consumers and represent a huge opportunity for e-tailers to capture new revenue.

Cisco says handsets will soon be the "fourth channel" for retailers, taking their place alongside physical stores, Web sites and catalogues.

However, according to a recent survey by Harris Interactive, over half of US consumers - 53% - have no interest in using their handsets for banking or commerce.